In the U.S. alone approximately one million women will have breast biopsies because of irregular mammograms and palpable abnormalities. Biopsies can be done in a number of different ways for non-palpable lesions, including surgical excisional biopsies and stereotactic and ultrasound guided needle breast biopsies. In the case of image directed biopsy, the radiologist or other physician takes a small sample of the irregular tissue for laboratory analysis. If the biopsy proves to be malignant, additional surgery (typically a lumpectomy or a mastectomy) is required. In the case of needle biopsies, the patient then returns to the radiologist a day or two later where the biopsy site (the site of the lesion) is relocated by method called needle localization, a preoperative localization in preparation for the surgery.
Locating the previously biopsied area after surgical excision type of biopsy is usually not a problem because of the deformity caused by the surgery. However, if the biopsy had been done with an image directed needle technique, as is common, help in relocating the biopsy site is needed. One procedure to permit the biopsy site to be relocated by the radiologist during preoperative localization is to leave some of the suspicious calcifications; this has its drawbacks.
Another way to help the radiologist relocate the biopsy site involves the use of a small metallic surgical clip, such as those made by Biopsys. The metallic clip can be deployed through the biopsy needle, and is left at the biopsy site at the time of the original biopsy. With the metallic clip as a guide, the radiologist typically inserts a barbed or hooked wire, such as the Hawkins, Kopans, Homer, Sadowski, and other needles, back into the patient""s breast and positions the tip of the wire at the biopsy site using mammography to document the placement. The patient is then taken to the operating room with the needle apparatus sticking out of the patient""s breast. While the clip provides a good indication of the biopsy site to the radiologist during preoperative localization, the clip remains permanently within the 80% of patients with benign diagnoses. Also, because the clip is necessarily attached to a single position at the periphery of the biopsy site, rather than the center of the biopsy site, its location may provide a misleading indication of the location of diseased tissue during any subsequent medical intervention. The clip is also relatively expensive. In addition, the soft nature of breast tissue permits the tip of the barbed or hooked needle to be relatively easily dislodged from the biopsy site. The surgeon typically pulls on the needle to help locate the area to be removed. This pulling motion during the excision may be responsible more than any other single factor for the movement of the needle. Additionally, these devices are not easily felt by external palpation and the tip is difficult to locate without dissection into the tissues; this prevents a surgical approach which may be more cosmetically advantageous and surgically appropriate than dissecting along the tract of the needle.
Another localization method involves the use of laser light from the tip of a optical fiber connected to a laser. A pair of hooks at the tip of the optical fiber secures the tip at the biopsy site; the glow indicates the position of the tip through several centimeters of breast tissue. This procedure suffers from some of the same problems associated with the use of barbed or hooked wires. Another preoperative localization procedure injects medical-grade powdered carbon suspension from the lesion to the skin surface. This procedure also has certain problems, including the creation of discontinuities along the carbon trail.
The present invention is directed to a target tissue localization device including an elongate placement device having first and second members being longitudinally movable relative to one another. An anchor is secured to the first and second members and is movable from a first, radially contracted configuration to a second, radially expanded configuration. The placement device and anchor are sized and configured for use in localization of target tissue. According to one aspect of the invention the anchor is a tubular mesh anchor. According to another aspect of the invention the anchor has a sufficiently large cross-sectional area when in the second, radially expanded configuration to substantially eliminate inadvertent dislodgment of the anchor once radially-expanded.
A further aspect of the invention relates to a method for localizing target tissue including determining the location of the target tissue and passing the distal end of an elongate localization device through the patient""s skin and to the target tissue to create a tissue track between the patient""s skin and the target tissue. The target tissue includes a near side toward the patient""s skin and a far side opposite the near side. The localization device includes an anchor element secured to a placement device, the placement device extending from the anchor element along the tissue track and through the patient""s skin. The anchor element is located at the target tissue and expanded to an expanded configuration. According to one aspect of the method the anchor element is located on the far side of the target tissue. According to another aspect of the method, the localization device is selected with an anchor which is palpable at the patient""s target tissue so that the target tissue can be relocated at least in part by palpation of the patient to locate the anchor; according to this aspect of the invention, at least a sample of the relocated target tissue is removed. The elongate localization device can be used as a guide or guide wire for further diagnostic of therapeutic procedures.
In preferred embodiment of the invention the anchor is a tubular mesh anchor which can be placed into a disk-like shape when in the fully expanded configuration or in a more flattened spherical shape, that is not as flat as the disk-like shape, which may aid in palpability. The anchor may also be in other forms such as a Malecot-type of radially expandable anchor. Another anchor embodiment could be deployed from the end of a hollow sheath and include numerous resilient curved projections which extend generally radially outwardly to fully surround the sheath.
The invention may find particular utility as an aid in the removal of small, difficult-to-grasp body structures, such as lymph nodes or other tissue that is difficult to grasp. The anchor could be positioned behind or inside a lymph node targeted for removal; lymph node removal can be aided by leaving the anchor in its expanded position so that after the surgeon cuts down to the lymph node, the lymph node, some surrounding tissue and the entire localization device can be removed for further analysis.
In some situations the anchor may be left in a partially or fully radially-expanded condition and used to pull the target tissue from the patient, typically with the aid of the surgeon opening the tissue track. For example, for tumor removal of the breast, the anchor may be used in a partially or fully expanded condition so that the tumor and surrounding margins can be removed during lumpectomy. Similar procedures can be used in regions other than the breast.
The invention may also include structure which may enhance ultrasound visibility. Invention may include certain treatment, grooves, slits, or other structure to enhance the ultrasonic visibility of the placement device or the delivery needle, or both. Also, the mesh anchor may provide sufficient reflectivity so that treatment of the placement device and delivery needle is not required. Other techniques for enhancing remote visualization, such as radiopaque markers, can also be used.
The invention is primarily related to mammographic localization, but may find utility with other areas of imaging including ultrasound, thoracoscopy, nuclear medicine, MRI, computed tomography, plain film and any other image guided technology.
The present invention provides a simple, relatively inexpensive, very stable localization device to locate a lesion or other target tissue, typically within the breast of a patient, for subsequent biopsy, excision, intervention, or other purpose. The localization device is easy to insert, deploy, reposition if needed, and remains anchored at the target site substantially better than conventional localization needles. Further, the invention aids relocation of the target tissue by being configured to permit location by palpation by the surgeon in the operating suite. This permits the surgeon to proceed using much less radical techniques, which may be both cosmetically and surgically advantageous.
Other features and advantages of the invention will appear from the following description in which the preferred the embodiments have been set forth in detail in conjunction with the accompanying drawings.